Radio frequency identification (RFID) systems may be used for a number of applications, such as managing inventory, electronic access control, security systems, automatic identification of cars on toll roads and electronic article surveillance (EAS). Ultra-high frequency (UHF) (860-960 Mega Hertz (MHz)) or microwave (2.45 Giga Hertz (GHz)) RFID systems may include a RFID reader and a RFID device. The RFID reader may transmit a radio-frequency carrier signal via an antenna to the RFID device, such as an RFID inlay or RFID tag. The RFID device may respond to the carrier signal with a data signal encoded with information stored by the RFID device. The antenna connected with the reader should be tuned to operate within a predetermined operating frequency band, usually preferred broadband frequency covering the operating frequency band, such as 860-960 MHz. Known RFID antennas are designed to operate in a sub-band of this frequency in the far field of the antenna. However, many applications involve reading an RFID tag in the near field of the antenna of the reader.
It is therefore desirable to have an antenna that operates substantially throughout significant portions of a broad frequency band in the near field of the antenna for RFID security applications as well as other RFID applications.